Atrophy
This process is called contraction. Muscles shorten or contract to produce movement.
These are found in muscle cells. The action causes contractions. They cause a sliding or shortening movement.
the movement of muscles which keeps the surface for gaseous supplied with oxygen causes breathing
Locomotion
In biological theory, some biologists suspect the shortening of sacromeres causes aging.
The movement is caused by the cremasteric muscles. Here is more information: http://en.wikipedia.org/wiki/Testicle
Agonist is a classification used to describe a muscle which causes specific movement or several movements through the process of contraction. This is a term for skeletal muscles, usually. Agonists are also sometimes called "prime movers" since they are the muscles being considered that are primarily responsible for generating a specific movement.
Smooth muscles
Your muscles cramp up after exercise if you do not stretch
Strabismus can be caused by a defect in muscles or the part of the brain that controls eye movement.
A snake's muscles can still contract and move even after it has died because of a chemical reaction called rigor mortis. This reaction causes the muscles to stiffen and contract, leading to the appearance of movement in the snake's body.
When plate movement causes rocks to break it is call an earthquake.